The present invention relates to an active matrix type liquid crystal display device manufactured by utilizing the thin film technique, and also relates to a picture element selective transistor which plays an important role in the liquid crystal display device.
Conventionally, in a general active matrix type thin film display device, as described, for example, in the U.S. Pat. No. 3,840,695, a thin film transistor with a staggered structure as shown in FIG. 2, has been utilized for picture element selective transistors, and a channel region (for example a-Si layer) 3 of the thin film transistor has normally a certain thickness, for example, 2000 .ANG. to 4000 .ANG..
Because such a channel region exhibits a highly efficient photoelectric effect, a light-shielding thin film layer 9 has to be provided when the thin film transistor is utilized in a liquid crystal display device, and therefore the process of making becomes complicated, and the efficiency of the transistor is often lowered.